DGT passive sampling device and method for drinking groundwater detection

Abstract

The invention discloses a DGT passive sampling device and method for drinking groundwater detection. The device comprises a bearing and supporting mechanism and a plurality of passive samplers arranged on the bearing and supporting mechanism, the bearing and supporting mechanism comprises a bearing and supporting column body; a plurality of sampler mounting holes are formed in the side surface of the bearing and supporting column body; the passive sampler comprises a sampler supporting outer barrel shell which is arranged in the sampler mounting hole and is coaxial with the sampler mounting hole, a membrane group mounting barrel shell with an opening in one end is arranged in the sampler supporting outer barrel shell in a sliding manner, and a composite gradient diffusion membrane group is fixed in the membrane group mounting barrel shell; the multi-type pollutant integrated accurate collection is achieved, the data representativeness and accuracy are improved, the designed composite gradient diffusion membrane set is of a series-connection integrated multi-layer structure, targeted diffusion and adsorption of anions, cations and neutral organic pollutants in underground water can be achieved at the same time, and the detection accuracy is improved. Full-coverage sampling of key pollutants of drinking underground water can be completed at a time, and the detection efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of water pollution detection technology, specifically to a DGT passive sampling device and method for detecting drinking groundwater. Background Technology

[0002] Emerging pollutants (ECs) have become a class of pollutants of great concern in recent years. These are pollutants that already exist in the environment but are not yet subject to relevant regulations, and may pose a threat to human health and the ecological environment. On May 4, 2022, the State Council issued the "Action Plan for the Control of Emerging Pollutants," elevating the research and prevention of emerging pollutants to a new level. Conducting research on emerging pollutants is an important strategic task and a significant requirement for improving environmental quality and achieving sustainable development in the future.

[0003] Groundwater is the most reliable perennial freshwater resource on Earth. It maintains the flow and water level of rivers and lakes, and is crucial to ecosystems and public health, especially in arid regions like Xinjiang. Due to industrial and agricultural activities, large amounts of new pollutants are discharged into groundwater, harming its quality and agricultural safety. Groundwater pollution is characterized by its insidious nature, long-term duration, and difficulty in reversing its effects. Investigating whether new pollutants exist in drinking water (groundwater), and what their pollution characteristics and risks are, is of significant scientific importance. It not only provides data support and technical assurance for monitoring new groundwater pollutants and a scientific basis for further detailed investigations of groundwater conditions and centralized drinking water source pollution prevention and control management, but also provides data and technical support and reserves for the prevention and control of new pollutants, and even serves as crucial scientific support for regional ecological environment and the promotion of high-quality development. Summary of the Invention

[0004] The purpose of this invention is to provide a DGT passive sampling device and method for drinking groundwater detection, which has the function of integrated and accurate collection of multiple types of pollutants.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A passive sampling device for drinking groundwater testing includes a support structure and multiple passive samplers mounted on the support structure. The support mechanism includes a support column, and the side of the support column has a plurality of sampler mounting holes extending radially therefrom; The passive sampler includes a sampler support outer shell disposed in the sampler mounting hole and arranged coaxially therewith, a membrane assembly mounting shell with one end open is slidably disposed inside the sampler support outer shell, and a composite gradient diffusion membrane assembly is fixed inside the membrane assembly mounting shell. The top of the supporting column is fixed with a cable installation ring.

[0006] Preferably, the composite gradient diffusion membrane assembly comprises a protective membrane, an anion selective diffusion membrane, an anion targeted adsorption membrane, a cation selective diffusion membrane, a cation targeted adsorption membrane, a neutral organic selective diffusion membrane, and a neutral organic targeted adsorption membrane connected in sequence. When the composite gradient diffusion membrane module is installed into the membrane module mounting shell, the neutral organic targeted adsorption membrane is placed close to the inner end of the membrane module mounting shell, and the protective membrane is flush with the open end of the membrane module mounting shell. The diameters of the anion selective diffusion membrane, anion targeted adsorption membrane, cation selective diffusion membrane, cation targeted adsorption membrane, neutral organic selective diffusion membrane, and neutral organic targeted adsorption membrane are the same as the inner diameter of the membrane assembly mounting shell, while the diameter of the protective membrane is the same as the outer diameter of the membrane assembly mounting shell.

[0007] Note: The composite gradient diffusion membrane module can simultaneously achieve targeted diffusion and adsorption of anions, cations and neutral organic pollutants in groundwater, eliminating the need for multiple replacements of the sampling membrane or device, and completing the sampling of key pollutants in drinking groundwater in a single operation.

[0008] Preferably, the end of the sampler support outer shell near the opening of the membrane module mounting shell is the water inlet end. The water inlet end of the sampler support outer shell is provided with a pretreatment anti-clogging mechanism. The pretreatment anti-clogging mechanism includes an anti-clogging support tube shell that is slidably connected inside the sampler support outer shell. The outer side of the anti-clogging support tube shell is provided with multiple sealing ring grooves. A rubber sealing ring is fixed in the sealing ring groove. The rubber sealing ring and the inner side wall of the sampler support outer shell are pressurized and sealed together. One end of the anti-clogging support tube shell inside the sampler support outer shell is in pressure contact with the open end of the membrane module installation shell; The sampler support outer shell has a threaded connection to a sealing and clamping end cap. The sealing and clamping end cap has a through hole that runs along the axis of the sampler support outer shell. A clamping ring is fixed to the outside of the anti-clogging support shell. The clamping ring is in contact with the inner end face of the sealing and clamping end cap. The end of the anti-clogging support tube shell, away from the membrane module mounting shell, extends out through the perforation; The anti-clogging support tube shell is provided with a filter-blocking support ring at the end away from the membrane module installation shell, and a hemispherical ceramic hemispherical filter shell is fixed on the side of the filter-blocking support ring away from the anti-clogging support tube shell. Multiple magnetic connection holes are provided on the end face of the anti-clogging support tube shell away from the membrane module installation shell. A fastening permanent magnet is fixed at the bottom of the magnetic connection hole. Multiple magnetic connection columns are fixed on the side of the filter support ring near the anti-clogging support tube shell. The multiple magnetic connection columns are slidably connected to each magnetic connection hole. The ceramic hemispherical filter housing has multiple micropores with a diameter of μm.

[0009] Note: The pretreatment anti-clogging mechanism can effectively intercept large particulate impurities such as silt and colloids in groundwater, preventing membrane blockage at the source.

[0010] Preferably, the end of the sampler support outer shell away from the opening of the membrane assembly mounting shell is a closed end. The closed end of the sampler support outer shell is provided with a pressure-resistant sealing mechanism. The pressure-resistant sealing mechanism includes a pressure-resistant sealing end cap that is threadedly fixed to the closed end of the sampler support outer shell. A limiting support shell that is coaxially arranged with the sampler support outer shell is fixed inside the pressure-resistant sealing end cap. A limiting support column that is coaxially arranged with the sampler support outer shell is fixed to the closed end of the membrane assembly mounting shell. The limiting support column is slidably connected in the limiting support shell. A limiting support spring is provided between the limiting support column and the inner end of the limiting support cylinder shell for top-pressure fit.

[0011] Explanation: The pressure-resistant sealing mechanism can withstand the water pressure impact of groundwater at different depths and prevent leakage. The membrane module installation shell forms an adaptive top-pressure structure through the limiting support column, the limiting support shell and the limiting support spring. The spring continuously provides the pushing force, so that the protective membrane is always clamped between the membrane module installation shell and the anti-clogging support shell. Even if the groundwater pressure fluctuates or the water flow impacts, the membrane module position can be kept fixed and the diffusion path can remain unchanged, ensuring the consistency of long-term sampling.

[0012] Preferably, the sampler support outer shell is connected to the sampler mounting hole via a quick-release mechanism. The quick-release mechanism includes a quick-release support ring fixed in the sampler mounting hole, and the sampler support outer shell is slidably connected in the quick-release support ring. Multiple quick-release support blocks are fixed on the outer side of the sampler support outer shell. Each quick-release support block has two quick-release constraint plates that extend circumferentially around the sampler support outer shell. The two quick-release constraint plates on each quick-release support block form a group. Each group of quick-release constraint plates has a quick-release constraint groove extending radially along the outer shell of the sampler support on the side closest to each other. Multiple quick-release constraint connecting posts extending radially are fixed on the inner wall of the sampler mounting hole. The multiple quick-release constraint connecting posts are engaged in each group of quick-release constraint grooves.

[0013] Note: The quick-release constraint connecting post snaps into the groove of the quick-release constraint clamp. The sampler can be fixed by rotating it clockwise and disassembled by rotating it counterclockwise, which can improve the efficiency of on-site assembly, well insertion and recovery.

[0014] Preferably, a distributed monitoring mechanism is provided on the outside of the sampler support outer shell. The distributed monitoring mechanism includes multiple distributed monitoring support columns fixed on the outside of the sampler support outer shell. A monitoring receiving hole is opened at the end of the distributed monitoring support column away from the sampler support outer shell. A water environment monitoring sensor is installed in the monitoring receiving hole, and a monitoring protective filter is fixed at the opening of the monitoring receiving hole.

[0015] Note: Distributed monitoring agencies can record key environmental parameters of groundwater in real time while sampling. By combining environmental parameters with DGT sampling data, the impact of temperature, pH, and dissolved oxygen on pollutant diffusion can be accurately analyzed, significantly improving the accuracy of subsequent pollutant concentration calculations.

[0016] The present invention also provides a passive sampling method for DGT in drinking groundwater detection, based on the above-mentioned passive sampling device for DGT in drinking groundwater detection, comprising the following steps: S1. Drilling sampling wells: Using drilling equipment, a sampling well is drilled that is connected to the groundwater to be tested; S2. Assembly of the sampling device: First, the composite gradient diffusion membrane is assembled into the membrane assembly mounting shell. Then, the membrane assembly mounting shell is installed into the sampler support outer shell. Finally, the sampler support outer shell is installed in the sampler mounting hole, with the opening of the membrane assembly mounting shell facing outwards. S3. Sampling device placement in the well: One end of a cable is fixed to the cable installation ring. The installed load-bearing support column is placed into the sampling well. Under the traction and release of the cable, the load-bearing support column is gradually sent into the sampling well until the entire load-bearing support column is submerged in groundwater. Finally, the other end of the cable is fixed to the ground. S4, Passive sampling wait: The entire load-bearing support column is continuously submerged in groundwater for 7 to 28 days; S5. Sampling device recovery: After the immersion period is over, the entire supporting column is removed from the sampling well by cable traction. Then, the outer shell of the sampler support is removed from the sampler mounting hole, the membrane assembly mounting shell is removed from the outer shell of the sampler support, and finally, the composite gradient diffusion membrane assembly is removed from the membrane assembly mounting shell and placed into a clean storage box to be brought back to the testing laboratory.

[0017] Compared with the prior art, the beneficial effects of the present invention are reflected in the following aspects: 1. The present invention has a reasonable structural design and can accurately collect multiple types of pollutants in an integrated manner, which improves the representativeness and accuracy of the data. The composite gradient diffusion membrane module designed in this invention integrates multiple layers in series, which can simultaneously achieve targeted diffusion and adsorption of anions, cations and neutral organic pollutants in groundwater. It can complete the full coverage sampling of key pollutants in drinking groundwater in one go, which greatly improves the detection efficiency. 2. This invention is easy to operate and has a multi-level protection and adaptive structure, which can ensure long-term sampling stability. The pretreatment anti-clogging mechanism can effectively solve the problem of groundwater impurities. The water inlet adopts a hemispherical ceramic hemispherical filter shell, which can reduce the water flow scouring resistance and effectively intercept large particulate impurities such as silt and colloids in groundwater, preventing membrane blockage from the source. 3. The ceramic hemispherical filter housing of the present invention is fixed by magnetic connection, which is convenient for disassembly, cleaning and replacement. After long-term sampling, the filter housing can be cleaned quickly to ensure that the sampling channel is unobstructed. At the same time, the anti-clogging support tube shell is sealed with the sampler support outer cylinder shell by a rubber sealing ring and is fixed by the thread of the sealing clamp end cap to form a double sealing protection, which completely prevents impurities from entering the membrane module area and further improves the sampling stability. 4. This invention features a distributed monitoring mechanism that enables simultaneous sampling and environmental parameter acquisition. The outer shell of the sampler is equipped with various distributed water environment monitoring sensors, including temperature, pH, and dissolved oxygen sensors. These sensors are protected from interference by a monitoring and protective filter. Key environmental parameters of groundwater can be recorded in real time during sampling. Combining these environmental parameters with DGT sampling data allows for precise analysis of the impact of temperature, pH, and dissolved oxygen on pollutant diffusion, significantly improving the accuracy of subsequent pollutant concentration calculations and providing a more comprehensive basis for drinking groundwater safety assessment. 5. The quick-release mechanism of the present invention enables tool-free quick installation and disassembly. The sampler support outer shell of the passive sampler and the sampler mounting hole of the bearing support column are connected by a rotary snap-fit ​​quick-release mechanism. The quick-release constraint connecting column is snapped into the groove of the quick-release constraint clamp. The sampler can be fixed by rotating it clockwise and disassembled by rotating it counterclockwise. This greatly improves the efficiency of on-site assembly, well insertion and recovery operations, and is especially suitable for the convenience requirements of field drilling sampling. Attached Figure Description

[0018] Figure 1 This is the front view of the present invention; Figure 2 This is a schematic diagram of the passive sampler of the present invention; Figure 3 This is a schematic diagram of the structure of the composite gradient diffusion membrane assembly of the present invention; Figure 4 This is a left view of the quick-release mechanism of the present invention; Figure 5 This is a top view of the quick-release support block of the present invention.

[0019] In the diagram, 10-bearing support mechanism, 101-cable installation lifting ring, 11-bearing support column, 110-sampler mounting hole, 20-passive sampler, 21-sampler support outer shell, 22-membrane module installation shell, 23-composite gradient diffusion membrane module, 231-protective membrane, 232-anion selective diffusion membrane, 233-anion targeted adsorption membrane, 234-cation selective diffusion membrane, 235-cation targeted adsorption membrane, 236-neutral organic selective diffusion membrane, 237-neutral organic targeted adsorption membrane, 30-pretreatment anti-clogging mechanism, 31-anti-clogging support tube shell, 311-sealing ring groove, 312-rubber sealing ring, 313-clamping ring, 32 -Sealed clamping end cap, 321-Perforation, 33-Filter support ring, 331-Ceramic hemispherical filter housing, 332-Magnetic connection hole, 333-Fixed magnetic permanent magnet, 334-Magnetic connection column, 40-Pressure-resistant sealing mechanism, 41-Pressure-resistant sealing end cap, 42-Limiting support cylinder, 43-Limiting support column, 431-Limiting support spring, 50-Quick release mechanism, 51-Quick release support ring, 52-Quick release support block, 53-Quick release constraint clamp, 531-Quick release constraint groove, 54-Quick release constraint connection column, 60-Distributed monitoring mechanism, 61-Distributed monitoring support column, 610-Monitoring receiving hole, 611-Monitoring protective filter screen, 62-Water environment monitoring sensor. Detailed Implementation

[0020] The following is combined Figures 1-5 The present invention will be described in detail. For ease of description, the orientations mentioned below are defined as follows: The directions of up, down, left, right, front, and back mentioned below are consistent with the directions of up, down, left, right, front, and back in the projection relationship of the respective main view or structural schematic diagram.

[0021] Example 1: A DGT passive sampling device for drinking groundwater detection, such as Figure 1 As shown, it includes a support structure 10 and a plurality of passive samplers 20 disposed on the support structure 10; The support mechanism 10 includes a support column 11, and the support column 11 has a plurality of sampler mounting holes 110 extending radially therefrom on its side. like Figure 1 As shown, the passive sampler 20 includes a sampler support outer shell 21 disposed in and coaxially arranged with the sampler mounting hole 110, such as... Figure 2 As shown, a membrane assembly mounting shell 22 with one end open is slidably provided inside the sampler support outer shell 21, and a composite gradient diffusion membrane assembly 23 is fixed inside the membrane assembly mounting shell 22. The top of the supporting column 11 is fixed with a cable installation ring 101.

[0022] like Figure 3As shown, the composite gradient diffusion membrane group 23 includes a protective membrane 231, anion selective diffusion membrane 232, anion targeted adsorption membrane 233, cation selective diffusion membrane 234, cation targeted adsorption membrane 235, neutral organic selective diffusion membrane 236 and neutral organic targeted adsorption membrane 237 connected in sequence. When the composite gradient diffusion membrane module 23 is installed into the membrane module mounting shell 22, the neutral organic targeted adsorption membrane 237 is brought close to the inner end of the membrane module mounting shell 22, and the protective membrane 231 is flush with the open end of the membrane module mounting shell 22. The diameters of the anion selective diffusion membrane 232, the anion targeted adsorption membrane 233, the cation selective diffusion membrane 234, the cation targeted adsorption membrane 235, the neutral organic selective diffusion membrane 236, and the neutral organic targeted adsorption membrane 237 are the same as the inner diameter of the membrane assembly mounting shell 22, and the diameter of the protective membrane 231 is the same as the outer diameter of the membrane assembly mounting shell 22. The protective membrane 231, anion selective diffusion membrane 232, anion targeted adsorption membrane 233, cation selective diffusion membrane 234, cation targeted adsorption membrane 235, neutral organic selective diffusion membrane 236 and neutral organic targeted adsorption membrane 237 in the composite gradient diffusion membrane group 23 are all commercially available products of the prior art. Protective membrane 231 can be, for example, a PVDF filter membrane of model HVLP04700 from Millipore; For example, an anion selective diffusion membrane 232 can be a Fumatech FAA-3-50 anion exchange membrane. For example, anion-targeted adsorption membrane 233 can be a Chelex 100 chelating resin membrane from Sigma-Aldrich. The cation selective diffusion membrane 234 can be, for example, the Nafion™ 117 perfluorosulfonic acid cation exchange membrane from Chemours. The cation-targeted adsorption membrane 235 can be, for example, the Amberlite™ IRC747 chelating adsorption membrane from Rohm and Haas. Neutral organic selective diffusion membrane 236 can be, for example, Agilent's Bond Elut® PPL solid phase extraction membrane; Neutral organic targeted adsorption membrane 237 can be, for example, Waters' Oasis® HLB Disk solid phase extraction membrane.

[0023] Example 2: This example describes a passive sampling method for DGT in drinking groundwater testing, based on the passive sampling device for DGT in drinking groundwater testing described in Example 1 above, including the following steps: S1. Drilling sampling wells: Using existing drilling equipment, a sampling well connected to the groundwater to be tested is drilled; S2. Assembly of the sampling device: First, the composite gradient diffusion membrane module 23 is installed into the membrane module mounting shell 22. Then, the membrane module mounting shell 22 is installed into the sampler support outer shell 21. Finally, the sampler support outer shell 21 is installed in the sampler mounting hole 110, with the opening of the membrane module mounting shell 22 facing outward. S3. Sampling device placement in the well: One end of a cable is fixed to the cable installation ring 101. The installed load-bearing support column 11 is placed into the sampling well. Under the traction and release of the cable, the load-bearing support column 11 is gradually sent into the sampling well until the entire load-bearing support column 11 is submerged in the groundwater. Finally, the other end of the cable is fixed to the ground. S4, Passive sampling wait: The entire load-bearing support column 11 was continuously submerged in groundwater for 7 days; S5. Sampling device recovery: After the immersion period is over, the entire supporting column 11 is removed from the sampling well by cable pulling. Then, the sampler support outer shell 21 is removed from the sampler mounting hole 110, the membrane assembly mounting shell 22 is removed from the sampler support outer shell 21, and finally the composite gradient diffusion membrane assembly 23 is removed from the membrane assembly mounting shell 22. The composite gradient diffusion membrane assembly 23 is placed in a clean storage box and taken back to the testing laboratory.

[0024] Example 3: Based on Example 1, such as Figure 2 As shown, the end of the sampler support outer shell 21 near the opening of the membrane module mounting shell 22 is the water inlet end. The water inlet end of the sampler support outer shell 21 is provided with a pretreatment anti-clogging mechanism 30. The pretreatment anti-clogging mechanism 30 includes an anti-clogging support tube shell 31 that is slidably connected inside the sampler support outer shell 21. The outer side of the anti-clogging support tube shell 31 is provided with multiple sealing ring grooves 311. A rubber sealing ring 312 is fixed in the sealing ring groove 311. The rubber sealing ring 312 and the inner side wall of the sampler support outer shell 21 are press-sealed together. One end of the anti-clogging support shell 31, which is located inside the sampler support outer shell 21, is in pressure contact with the open end of the membrane module mounting shell 22. The water inlet end of the sampler support outer cylinder shell 21 is threadedly connected to a sealing clamping end cap 32. The sealing clamping end cap 32 has a through hole 321 that runs through the axis of the sampler support outer cylinder shell 21. A clamping ring 313 is fixed on the outside of the anti-clogging support tube shell 31. The clamping ring 313 is in contact with the inner end face of the sealing clamping end cap 32. One end of the anti-clogging support tube shell 31, away from the membrane module mounting shell 22, extends out from the perforation 321; The anti-clogging support tube shell 31 is provided with a filter-blocking support ring 33 at one end away from the membrane module installation shell 22, and a hemispherical ceramic hemispherical filter shell 331 is fixed on the side of the filter-blocking support ring 33 away from the anti-clogging support tube shell 31. Multiple magnetic connection holes 332 are provided on the end face of the anti-clogging support tube shell 31 away from the membrane module installation cylinder shell 22. A fastening magnetic permanent magnet 333 is fixed at the bottom of the magnetic connection hole 332. Multiple magnetic connection columns 334 are fixed on the side of the filter support ring 33 near the anti-clogging support tube shell 31. The multiple magnetic connection columns 334 are slidably connected in each magnetic connection hole 332. The ceramic hemispherical filter housing 331 has multiple micropores with a diameter of 0.3 μm.

[0025] like Figure 2 As shown, the end of the sampler support outer shell 21 away from the opening of the membrane assembly mounting shell 22 is a closed end. The closed end of the sampler support outer shell 21 is provided with a pressure-resistant sealing mechanism 40. The pressure-resistant sealing mechanism 40 includes a pressure-resistant sealing end cap 41 that is threadedly fixed to the closed end of the sampler support outer shell 21. A limiting support shell 42 that is coaxially arranged with the sampler support outer shell 21 is fixed inside the pressure-resistant sealing end cap 41. A limiting support column 43 that is coaxially arranged with the sampler support outer shell 21 is fixed to the closed end of the membrane assembly mounting shell 22. The limiting support column 43 is slidably connected in the limiting support shell 42. A limiting support spring 431 is provided between the limiting support column 43 and the inner end of the limiting support cylinder shell 42 for pressing and engaging.

[0026] like Figure 1 As shown, the sampler support outer cylinder shell 21 is connected to the sampler mounting hole 110 through a quick-release mechanism 50. The quick-release mechanism 50 includes a quick-release support ring 51 fixed in the sampler mounting hole 110, and the sampler support outer cylinder shell 21 is slidably connected in the quick-release support ring 51. like Figure 2 As shown, multiple quick-release support blocks 52 are fixed to the outer side of the sampler support outer shell 21. Each quick-release support block 52 has two quick-release constraint plates 53 that extend circumferentially around the sampler support outer shell 21 fixed to its side. Figure 4 , Figure 5 As shown, the two quick-release constraint plates 53 on each quick-release support block 52 form a group. Each group of quick-release constraint plates 53 has a quick-release constraint groove 531 extending radially along the outer shell 21 of the sampler support on one side that is close to each other. Multiple quick-release constraint connecting posts 54 extending radially are fixed on the inner wall of the sampler mounting hole 110. The multiple quick-release constraint connecting posts 54 are engaged in each group of quick-release constraint grooves 531.

[0027] Example 4: This example describes a passive sampling method for drinking groundwater testing using DGT, based on the passive sampling device for drinking groundwater testing described in Example 3 above. The difference from Example 2 is that the assembly process of the passive sampler 20 in S2 is as follows: First, install the pretreatment anti-clogging mechanism 30 on the water inlet end of the sampler support outer cylinder shell 21. Slide the end of the anti-clogging support tube shell 31 with the rubber sealing ring 312 fixed into the water inlet end of the sampler support outer cylinder shell 21. Fit the through hole 321 of the sealing clamping end cap 32 onto the outside of the anti-clogging support tube shell 31. Tighten and fix the sealing clamping end cap 32 to the water inlet end of the sampler support outer cylinder shell 21 in the form of a threaded connection. The composite gradient diffusion membrane assembly 23 is installed into the membrane assembly mounting shell 22, and the protective film 231 is attached to the edge of the opening end of the membrane assembly mounting shell 22. The membrane assembly housing 22 containing the composite gradient diffusion membrane assembly 23 is slidably inserted into the sampler support outer housing 21 from the closed end of the sampler support outer housing 21. Finally, the pressure-resistant sealing mechanism 40 is installed at the closed end of the sampler support outer housing 21. First, the limiting support column 43 is aligned coaxially with the limiting support housing 42, and the limiting support spring 431 in the limiting support housing 42 is pressed against the limiting support column 43. Then, the pressure-resistant sealing end cap 41 is tightened and fixed to the closed end of the sampler support outer housing 21 in the form of a threaded connection. Under the elastic pressure of the limiting support spring 431, the protective film 231 is clamped between the open end of the membrane assembly mounting shell 22 and the inner end of the anti-clogging support tube shell 31. A ceramic hemispherical filter shell 331 is installed at one end of the anti-clogging support tube shell 31 outside the sampler support outer cylinder shell 21. Multiple magnetic connecting columns 334 are slidably pushed into each magnetic connecting hole 332. The entire filter-blocking support ring 33 and the ceramic hemispherical filter shell 331 are magnetically fixed to the outer end of the anti-clogging support tube shell 31 by the magnetic force between the fastening magnetic permanent magnet 333 and the magnetic connecting column 334.

[0028] The entire sampler support outer shell 21 is pushed into the sampler mounting hole 110 with the ceramic hemispherical filter shell 331 facing outwards. The sampler support outer shell 21 is slidably supported in the quick-release support ring 51. When the quick-release support block 52 and the quick-release constraint connecting post 54 are aligned in the circumferential direction around the sampler support outer shell 21, the sampler support outer shell 21 is rotated clockwise, causing the quick-release support block 52 and the quick-release constraint connecting post 54 to move closer to each other. This causes the quick-release constraint connecting post 54 to engage in the quick-release constraint groove 531 between the two quick-release constraint clamps 53, thus limiting and fixing the entire sampler support outer shell 21 and firmly constraining it in the sampler mounting hole 110.

[0029] Example 5: Based on Example 3, such as Figure 2 As shown, a distributed monitoring mechanism 60 is provided on the outside of the sampler support outer shell 21. The distributed monitoring mechanism 60 includes multiple distributed monitoring support columns 61 fixed on the outside of the sampler support outer shell 21. A monitoring receiving hole 610 is opened at the end of the distributed monitoring support column 61 away from the sampler support outer shell 21. A water environment monitoring sensor 62 is provided in the monitoring receiving hole 610. A monitoring protective filter screen 611 is fixed at the opening of the monitoring receiving hole 610.

[0030] Example 6: This example describes a passive DGT sampling method for drinking groundwater detection, based on the passive DGT sampling device for drinking groundwater detection described in Example 5 above. The difference from Example 4 is that in S4, during the continuous immersion process, a distributed monitoring mechanism 60 is used to monitor and record groundwater parameters in real time. The water environment monitoring sensor 62 is a commercially available product, including a temperature sensor, a pH sensor, and a dissolved oxygen sensor. The water environment monitoring sensor 62 is used to monitor the temperature, pH, and dissolved oxygen parameters of the groundwater in real time and record them in the memory. Later, the stored data can be exported by connecting to a computer via a data transmission line.

[0031] Example 7: The difference from Example 6 is that in S4, the entire load-bearing support column 11 is continuously submerged in groundwater for 21 days.

[0032] Example 8: The difference from Example 6 is that in S4, the entire load-bearing support column 11 is continuously submerged in groundwater for 28 days.

[0033] In practical application, the method of Example 1 was used to sample groundwater at a location in Xinjiang. Taking the novel organic pollutant bisphenol A as an example, the total amount of bisphenol A (M) eluted from the composite gradient diffusion membrane module 23 was 84 ng, and the opening area (A) at the open end of the membrane module mounting shell 22 was 4.91 cm². 2 The thickness Δg of the neutral organic selective diffusion membrane 236 is 0.02 cm, and the diffusion coefficient De of bisphenol A in the diffusion membrane is 5.2 × 10⁻⁶. −6 cm 2 / s, sampling time t is 604800 s; According to Fick's first law of diffusion, the time-weighted average concentration of bisphenol A in groundwater ( The calculation formula is: Substituting the above data into the calculation, we obtain the following results. It is 0.11 ng / cm 3 This translates to 0.11 μg / L, which is the commonly used unit for water environment concentration.

Claims

1. A DGT passive sampling device for drinking groundwater detection, characterized in that, It includes a support structure (10) and a plurality of passive samplers (20) disposed on the support structure (10); The bearing support mechanism (10) includes a bearing support column (11) with a plurality of sampler mounting holes (110) extending radially therefrom on its side. The passive sampler (20) includes a sampler support outer shell (21) disposed in the sampler mounting hole (110) and coaxially arranged therewith. A membrane assembly mounting shell (22) with one end open is slidably disposed inside the sampler support outer shell (21). A composite gradient diffusion membrane assembly (23) is fixed inside the membrane assembly mounting shell (22). The top of the load-bearing support column (11) is fixed with a cable installation ring (101).

2. The DGT passive sampling device for drinking groundwater detection according to claim 1, characterized in that, The composite gradient diffusion membrane group (23) includes a protective membrane (231), an anion selective diffusion membrane (232), an anion targeted adsorption membrane (233), a cation selective diffusion membrane (234), a cation targeted adsorption membrane (235), a neutral organic selective diffusion membrane (236), and a neutral organic targeted adsorption membrane (237) connected in sequence. When the composite gradient diffusion membrane module (23) is installed into the membrane module mounting shell (22), the neutral organic targeted adsorption membrane (237) is brought close to the inner end of the membrane module mounting shell (22), and the protective membrane (231) is flush with the open end of the membrane module mounting shell (22). The diameters of the anion selective diffusion membrane (232), the anion targeted adsorption membrane (233), the cation selective diffusion membrane (234), the cation targeted adsorption membrane (235), the neutral organic selective diffusion membrane (236), and the neutral organic targeted adsorption membrane (237) are the same as the inner diameter of the membrane assembly mounting shell (22), and the diameter of the protective membrane (231) is the same as the outer diameter of the membrane assembly mounting shell (22).

3. The DGT passive sampling device for drinking groundwater detection according to claim 1, characterized in that, The end of the sampler support outer shell (21) near the opening of the membrane assembly mounting shell (22) is the water inlet end. The water inlet end of the sampler support outer shell (21) is provided with a pretreatment anti-clogging mechanism (30). The pretreatment anti-clogging mechanism (30) includes an anti-clogging support tube shell (31) slidably connected in the sampler support outer shell (21). The outer side of the anti-clogging support tube shell (31) is provided with multiple sealing ring grooves (311). A rubber sealing ring (312) is fixed in the sealing ring groove (311). The rubber sealing ring (312) is press-sealed with the inner wall of the sampler support outer shell (21). The anti-clogging support shell (31) is located inside the sampler support outer shell (21) at one end, which is in pressure contact with the open end of the membrane assembly mounting shell (22). The water inlet end of the sampler support outer cylinder shell (21) is threadedly connected to a sealing clamping end cap (32). The sealing clamping end cap (32) has a through hole (321) that runs through the axis of the sampler support outer cylinder shell (21). A clamping ring (313) is fixed on the outside of the anti-clogging support tube shell (31). The clamping ring (313) is in contact with the inner end face of the sealing clamping end cap (32). The end of the anti-clogging support tube shell (31) away from the membrane assembly mounting shell (22) extends out from the perforation (321); The anti-clogging support tube shell (31) is provided with a filter-blocking support ring (33) at one end away from the membrane module mounting shell (22), and a hemispherical ceramic hemispherical filter shell (331) is fixed on the side of the filter-blocking support ring (33) away from the anti-clogging support tube shell (31). The anti-clogging support tube shell (31) has multiple magnetic connection holes (332) on the end face away from the membrane assembly mounting shell (22). A fastening magnetic permanent magnet (333) is fixed at the bottom of the magnetic connection hole (332). Multiple magnetic connection columns (334) are fixed on the side of the filter support ring (33) close to the anti-clogging support tube shell (31). The multiple magnetic connection columns (334) are slidably connected in each of the magnetic connection holes (332).

4. The DGT passive sampling device for drinking groundwater detection according to claim 1, characterized in that, The end of the sampler support outer shell (21) away from the opening of the membrane assembly mounting shell (22) is a closed end. The closed end of the sampler support outer shell (21) is provided with a pressure-resistant sealing mechanism (40). The pressure-resistant sealing mechanism (40) includes a pressure-resistant sealing end cap (41) that is threadedly fixed to the closed end of the sampler support outer shell (21). A limiting support shell (42) that is coaxially arranged with the sampler support outer shell (21) is fixed inside the pressure-resistant sealing end cap (41). A limiting support column (43) that is coaxially arranged with the sampler support outer shell (21) is fixed at the closed end of the membrane assembly mounting shell (22). The limiting support column (43) is slidably connected in the limiting support shell (42). A limiting support spring (431) is provided between the limiting support column (43) and the inner end of the limiting support cylinder (42) for pressing and engaging.

5. A DGT passive sampling device for drinking groundwater detection according to claim 1, characterized in that, The sampler support outer shell (21) is connected to the sampler mounting hole (110) via a quick-release mechanism (50). The quick-release mechanism (50) includes a quick-release support ring (51) fixed in the sampler mounting hole (110), and the sampler support outer shell (21) is slidably connected to the quick-release support ring (51). Multiple quick-release support blocks (52) are fixed on the outer side of the sampler support outer shell (21). Each quick-release support block (52) has two quick-release constraint plates (53) that extend circumferentially around the sampler support outer shell (21) fixed on its side. The two quick-release constraint plates (53) on each quick-release support block (52) form a group. Each group of quick-release constraint plates (53) has a quick-release constraint groove (531) that extends radially along the sampler support outer shell (21) on the side that is close to each other. Multiple quick-release constraint connecting posts (54) that extend radially along the inner wall of the sampler mounting hole (110) are fixed on it. The multiple quick-release constraint connecting posts (54) are engaged in each group of quick-release constraint grooves (531).

6. A DGT passive sampling device for drinking groundwater detection according to claim 1, characterized in that, A distributed monitoring mechanism (60) is provided on the outside of the sampler support outer shell (21). The distributed monitoring mechanism (60) includes multiple distributed monitoring support columns (61) fixed on the outside of the sampler support outer shell (21). A monitoring receiving hole (610) is opened at one end of the distributed monitoring support column (61) away from the sampler support outer shell (21). A water environment monitoring sensor (62) is provided in the monitoring receiving hole (610). A monitoring protective filter screen (611) is fixed at the opening of the monitoring receiving hole (610).

7. A passive sampling method for DGT in drinking groundwater detection, based on the passive sampling device for DGT in drinking groundwater detection according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Drilling sampling wells: Using drilling equipment, a sampling well is drilled that is connected to the groundwater to be tested; S2. Assembly of the sampling device: First, the composite gradient diffusion membrane module (23) is installed into the membrane module mounting shell (22). Then, the membrane module mounting shell (22) is installed into the sampler support outer shell (21). Finally, the sampler support outer shell (21) is installed in the sampler mounting hole (110), with the opening of the membrane module mounting shell (22) facing outward. S3. Sampling device placement in the well: One end of a cable is fixed to the cable installation ring (101), and the installed load-bearing support column (11) is placed into the sampling well. Under the traction and release of the cable, the load-bearing support column (11) is gradually sent into the sampling well until the entire load-bearing support column (11) is submerged in the groundwater. Finally, the other end of the cable is fixed to the ground. S4, Passive sampling wait: The entire supporting column (11) was continuously submerged in groundwater for 7 to 28 days; S5. Sampling device recovery: After the immersion period is over, the entire supporting column (11) is removed from the sampling well by cable pulling. Then, the sampler support outer shell (21) is removed from the sampler mounting hole (110), the membrane assembly mounting shell (22) is removed from the sampler support outer shell (21), and finally the composite gradient diffusion membrane assembly (23) is removed from the membrane assembly mounting shell (22). The composite gradient diffusion membrane assembly (23) is placed in a clean storage box and brought back to the testing laboratory.

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